Biomedical subjects

W M Hu

Publications and source records attributed to W M Hu.

14 recordsLinked to original sources

PubMed1992

Characterization of a Gy4 glycinin gene from soybean Glycine max cv. forrest.

The glycinin gene family encoding the glycinin subunits in soybean plants is composed of at least five gene members. A genomic clone lambda S312 containing the Gy4 gene from a genomic library of cv. Forrest was isolated and partially characterized. The organization of this gene was found to be similar to that of a null allele from cv. Raiden, but different from the Gy4 gene from cv. Dare. The complete nucleotide sequence of this gene has been determined. It is 2599 bp long consisting of four exons and three introns. Comparing the DNA sequences between this gene and the gene from Dare and a null allele from Raiden, the difference found in the coding region was 5'-GCAGTGCAAG-3' (nt 824 to 833) in the former case versus 5'-TGGAGTTGCAATT-3' (nt 1314 to 1326) in the latter case in the exon 2 domain, resulting in three amino acid differences and one amino acid absence. Some other differences were also found in the non-coding region. The coding sequence and 5'-flanking region of the Gy4 gene, when compared with that of other legumin genes as well as group 1 glycinin subunit genes, revealed some interesting features: (1) a transposable element-like sequence was found in the hypervariable region (HVR) of the exon 3 domain, which was lacking in the legumin and the glycinin group 1 genes; (2) in the 5'-flanking region from nt -145 to -1, two high-homology sequences were found: one from nt -141 to nt -132, the other from nt -118 to nt -92 which includes the 'legumin box' and the RY repeat element.

Amino Acid Sequence↗

PubMed1991

Characterization of the coronary vascular responses to platelet-activating factor in the isolated perfused heart.

Platelet-activating factor (PAF) is a potent phospholipid mediator with diverse in vivo and in vitro coronary vascular effects. In the present study, the coronary vascular responses to bolus injections of PAF were compared in rat hearts perfused under constant flow and under constant pressure. Low levels of PAF (1 pmol) produced vasodilatation only, while higher PAF concentrations (100 pmol) produced initial vasodilatation which was followed by a vasoconstriction under both experimental conditions. To determine species differences in PAF action, the effect of PAF was tested on perfused guinea pig hearts. Unlike in perfused rat hearts, only a dose-dependent vasoconstrictor response was observed in perfused guinea pig hearts following a bolus injection of 1 fmol to 10 pmol of PAF. The results from repeated injections of PAF indicated that depletion of vasoactive mediators induced by PAF or receptor desensitization may explain a failure of a second injection of PAF to initiate a vasoconstrictor response. After PAF injection, the coronary vascular response to leukotriene was not altered, indicating that the reduced vasoconstrictor effect of a second injection of PAF cannot be due to a reduced ability of the smooth muscle to constrict. The study demonstrates that similar coronary vascular responses to PAF are observed in perfused rat hearts under either constant flow rate or constant pressure and that some of the variable coronary vascular responses reported may be due to the difference between animal species.

Animals↗

PubMed1991

Differential actions of platelet-activating factor (PAF) receptor antagonists on the vasodilator and vasoconstrictor effects of PAF in the rat perfused heart.

Selectivity for blocking the coronary vasodilator and vasoconstrictor effects of platelet-activating factor (PAF) in the rat perfused heart was observed with different PAF antagonists. CV-6209 showed selectivity for blocking the vasodilator effect of PAF and a higher concentration (10 fold) was required to block the vasoconstrictor effect. The remaining PAF antagonists (FR-900452, WEB 2086 and BN-50739) showed selectivity for blocking the vasoconstrictor effect of PAF (10, 200 and 1000 fold respectively). A combination of low concentrations of CV-6209 (10 nM) with FR-900452 (5 microM) or WEB 2086 (0.5 microM) was effective in blocking both the vasodilator and vasoconstrictor effects of PAF. CV-6209 and WEB 2086 did not affect the vasodilator action of leukotriene B4 (LTB4) and the vasoconstrictor action of LTC4 and LTD4. Our results support the hypothesis that the functionally opposite effects of PAF in the rat perfused heart may be mediated by different PAF receptor subtypes.

Animals↗

PubMed1991

Interaction of vasoactive substances released by platelet-activating factor in the rat perfused heart.

1. The coronary vascular effects of platelet-activating factor (PAF) have been intensively studied and it has been proposed that they are mediated by the release of vasoactive substances. In this study, a cascade perfusion model using two rat perfused hearts was developed to investigate the properties of PAF-released vasoactive substances and the interplay of these substances. The properties of the vasoactive substances after an injection of PAF (100 pmol) in the rat perfused heart were examined by collecting the effluent from the first heart for the perfusion of a second (recipient) heart. The presence of vasoconstrictor substances in the effluent was characterized by an increase in the perfusion pressure of the recipient heart. 2. Previous exposure of the recipient heart of PAF (100 pmol) abolished the response of the heart to subsequent administration of PAF, but did not affect the response of the recipient heart to the effluent. This suggested that the coronary vasoconstrictor response of the recipient heart was not due to the presence of PAF in the effluent but to other vasoactive substances. 3. Pretreatment of the recipient heart with the leukotriene receptor antagonist, L-649,923 (5 microM), partially reduced the vasoconstrictor effect of the effluent. Pretreatment of the first heart with indomethacin (2.8 microM) also partially reduced the vasoconstrictor effect of the effluent. The combination of indomethacin pretreatment of the first heart and L-649,923 pretreatment of the recipient heart completely abolished the vasoconstrictor effect of the effluent suggesting that both prostaglandins and leukotrienes are involved in the vasoconstrictor effect of the effluent. 4. Pretreatment of both hearts with L-649,923 or the first heart with the leukotriene synthesis inhibitor (MK-886, 10 microM) completely abolished the vasoconstrictor effect of the effluent. This suggested that the indomethacin sensitive vasoconstrictor component of the effluent might be regulated by leukotrienes in the first heart. However, infusion of leukotrienes (LTB4, LTC4 and LTD4) to the first heart did not reproduce this vasoconstrictor component of the effluent in the recipient heart.5. In conclusion, our study demonstrated through the use of a leukotriene receptor antagonist, a leukotriene synthesis inhibitor and a cyclo-oxygenase inhibitor that the vasoconstrictor effect of the effluent of the rat perfused heart after an injection of PAF is mediated by leukotrienes and prostaglandins. The ability of leukotriene receptor blockade and inhibition of leukotriene synthesis to mimic the effect of indomethacin indicates that the production and/or release of cyclo-oxygenase products in the effluent by PAF can be modulated by leukotrienes. The inability of exogenously applied leukotrienes to modulate the production and/or the release of cyclo-oxygenase products in the effluent suggests that the PAF-induced production of prostaglandins may be mediated by intracellular leukotrienes or at sites not accessible to exogenously applied leukotrienes.

Animals↗

PubMed1989

Imaging diagnostic value of myxoma in cardiac chamber. An analysis of 23 cases.

Twenty-three patients with myxoma in the cardiac chamber were analysed from their clinical manifestations and imaging diagnoses. All the patients were confirmed pathologically and 22 of them were further confirmed by operation. In this series, 18 patients had the tumors in the left atria, 3 in the right atria, and 2 in the right ventricles. Diagnosing myxoma by CT and two-dimensional echocardiography was evaluated. The results suggest that to diagnose myxoma in the cardiac chamber, CT is as effective as sonography because it can display clear image, precise location and mobility of the tumor with the flowing blood stream in the cardiac chamber, and provide reliable indications for surgery.

Adolescent↗

PubMed1986